Capítulo 4: Configuração do Logback

Introdução

Logback é a implementação de logging padrão do Spring Boot. Este capítulo ensina como configurá-lo para diferentes ambientes.

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🎯 Objetivos do Capítulo

Ao final deste capítulo, você saberá:

1. ✅ Criar um arquivo logback-spring.xml
2. ✅ Configurar appenders (Console, File, Rolling)
3. ✅ Personalizar os padrões de log
4. ✅ Utilizar perfis do Spring
5. ✅ Configurar logs em JSON para produção

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1. Configuração Básica

Arquivo logback-spring.xml

Crie src/main/resources/logback-spring.xml:

<?xml version="1.0" encoding="UTF-8"?>
<configuration>

    <!-- Importa valores do Spring Boot -->
    <include resource="org/springframework/boot/logging/logback/defaults.xml"/>
    
    <!-- Variável para o nome da aplicação -->
    <springProperty scope="context" name="APP_NAME" source="spring.application.name" defaultValue="myapp"/>

    <!-- Console Appender -->
    <appender name="CONSOLE" class="ch.qos.logback.core.ConsoleAppender">
        <encoder>
            <pattern>%d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n</pattern>
        </encoder>
    </appender>

    <!-- Configuração padrão -->
    <root level="INFO">
        <appender-ref ref="CONSOLE"/>
    </root>
    
    <!-- Nível específico para sua aplicação -->
    <logger name="com.myapp" level="DEBUG"/>

</configuration>

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2. Padrões de Log

Sintaxe dos Padrões

Pattern	Descrição	Exemplo
%d\{format\}	Data/hora	2024-01-15 10:30:00
%thread	Nome da thread	http-nio-8080-exec-1
%level / %-5level	Nível (padded)	INFO
%logger\{n\}	Nome do logger (n chars)	c.m.s.UserService
%msg	Mensagem	User logged in
%n	Nova linha
%X\{key\}	Valor MDC	abc-123
%highlight()	Cores (console)

Exemplos de Padrões

<!-- Simples -->
<pattern>%d{HH:mm:ss} %-5level %logger{36} - %msg%n</pattern>
<!-- Output: 10:30:00 INFO  c.m.s.UserService - User logged in -->

<!-- Com MDC -->
<pattern>%d{HH:mm:ss} [%X{requestId}] [%X{userId}] %-5level %logger{36} - %msg%n</pattern>
<!-- Output: 10:30:00 [abc-123] [42] INFO  c.m.s.UserService - User logged in -->

<!-- Colorido para console -->
<pattern>%d{HH:mm:ss} %highlight(%-5level) %cyan(%logger{36}) - %msg%n</pattern>

<!-- Detalhado para arquivo -->
<pattern>%d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] [%X{requestId:-N/A}] %-5level %logger{50} - %msg%n</pattern>

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3. Appenders

Console Appender

<appender name="CONSOLE" class="ch.qos.logback.core.ConsoleAppender">
    <encoder>
        <pattern>%d{HH:mm:ss.SSS} %highlight(%-5level) %cyan(%logger{36}) - %msg%n</pattern>
    </encoder>
</appender>

File Appender (arquivo simples)

<appender name="FILE" class="ch.qos.logback.core.FileAppender">
    <file>logs/application.log</file>
    <append>true</append>
    <encoder>
        <pattern>%d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] %-5level %logger{50} - %msg%n</pattern>
    </encoder>
</appender>

Rolling File Appender (com rotação)

<appender name="ROLLING_FILE" class="ch.qos.logback.core.rolling.RollingFileAppender">
    <file>logs/application.log</file>
    
    <!-- Política de rotação -->
    <rollingPolicy class="ch.qos.logback.core.rolling.SizeAndTimeBasedRollingPolicy">
        <!-- Nome dos arquivos arquivados -->
        <fileNamePattern>logs/application.%d{yyyy-MM-dd}.%i.log.gz</fileNamePattern>
        <!-- Tamanho máximo por arquivo -->
        <maxFileSize>10MB</maxFileSize>
        <!-- Número de dias de retenção -->
        <maxHistory>30</maxHistory>
        <!-- Tamanho total máximo -->
        <totalSizeCap>1GB</totalSizeCap>
    </rollingPolicy>
    
    <encoder>
        <pattern>%d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] [%X{requestId}] %-5level %logger{50} - %msg%n</pattern>
    </encoder>
</appender>

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4. Perfis do Spring

Configuração por Perfil

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
    
    <include resource="org/springframework/boot/logging/logback/defaults.xml"/>
    
    <!-- Appender Console (sempre presente) -->
    <appender name="CONSOLE" class="ch.qos.logback.core.ConsoleAppender">
        <encoder>
            <pattern>%d{HH:mm:ss.SSS} %highlight(%-5level) %cyan(%logger{36}) - %msg%n</pattern>
        </encoder>
    </appender>

    <!-- ===== PERFIL DEV ===== -->
    <springProfile name="dev">
        <root level="INFO">
            <appender-ref ref="CONSOLE"/>
        </root>
        <logger name="com.myapp" level="DEBUG"/>
        <logger name="org.hibernate.SQL" level="DEBUG"/>
    </springProfile>

    <!-- ===== PERFIL PROD ===== -->
    <springProfile name="prod">
        
        <!-- Arquivo com rotação -->
        <appender name="FILE" class="ch.qos.logback.core.rolling.RollingFileAppender">
            <file>/var/log/myapp/application.log</file>
            <rollingPolicy class="ch.qos.logback.core.rolling.SizeAndTimeBasedRollingPolicy">
                <fileNamePattern>/var/log/myapp/application.%d{yyyy-MM-dd}.%i.log.gz</fileNamePattern>
                <maxFileSize>50MB</maxFileSize>
                <maxHistory>30</maxHistory>
                <totalSizeCap>5GB</totalSizeCap>
            </rollingPolicy>
            <encoder>
                <pattern>%d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] [%X{requestId}] %-5level %logger{50} - %msg%n</pattern>
            </encoder>
        </appender>
        
        <root level="WARN">
            <appender-ref ref="FILE"/>
        </root>
        <logger name="com.myapp" level="INFO"/>
    </springProfile>

    <!-- ===== PERFIL TEST ===== -->
    <springProfile name="test">
        <root level="WARN">
            <appender-ref ref="CONSOLE"/>
        </root>
        <logger name="com.myapp" level="INFO"/>
    </springProfile>

</configuration>

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5. Logs JSON para Produção

Por que JSON?

Logs texto:
2024-01-15 10:30:00 INFO UserService - User 42 logged in

Logs JSON (parseável por ELK, Datadog, etc.):
{"timestamp":"2024-01-15T10:30:00.000Z","level":"INFO","logger":"UserService","message":"User logged in","userId":42}

Dependência

<dependency>
    <groupId>net.logstash.logback</groupId>
    <artifactId>logstash-logback-encoder</artifactId>
    <version>7.4</version>
</dependency>

Configuração JSON

<!-- Appender JSON -->
<appender name="JSON_FILE" class="ch.qos.logback.core.rolling.RollingFileAppender">
    <file>/var/log/myapp/application.json</file>
    
    <rollingPolicy class="ch.qos.logback.core.rolling.SizeAndTimeBasedRollingPolicy">
        <fileNamePattern>/var/log/myapp/application.%d{yyyy-MM-dd}.%i.json.gz</fileNamePattern>
        <maxFileSize>50MB</maxFileSize>
        <maxHistory>7</maxHistory>
    </rollingPolicy>
    
    <!-- Encoder JSON -->
    <encoder class="net.logstash.logback.encoder.LogstashEncoder">
        <includeMdcKeyName>requestId</includeMdcKeyName>
        <includeMdcKeyName>userId</includeMdcKeyName>
        <customFields>{"app":"myapp","env":"prod"}</customFields>
    </encoder>
</appender>

<springProfile name="prod">
    <root level="INFO">
        <appender-ref ref="JSON_FILE"/>
    </root>
</springProfile>

Output JSON

{
    "@timestamp": "2024-01-15T10:30:00.000Z",
    "@version": "1",
    "message": "User logged in",
    "logger_name": "com.myapp.service.UserService",
    "thread_name": "http-nio-8080-exec-1",
    "level": "INFO",
    "requestId": "abc-123",
    "userId": "42",
    "app": "myapp",
    "env": "prod"
}

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6. Configuração Completa Profissional

<?xml version="1.0" encoding="UTF-8"?>
<configuration scan="true" scanPeriod="30 seconds">

    <include resource="org/springframework/boot/logging/logback/defaults.xml"/>
    
    <springProperty scope="context" name="APP_NAME" source="spring.application.name" defaultValue="myapp"/>
    <property name="LOG_PATH" value="${LOG_PATH:-logs}"/>

    <!-- ===== CONSOLE APPENDER ===== -->
    <appender name="CONSOLE" class="ch.qos.logback.core.ConsoleAppender">
        <encoder>
            <pattern>%d{HH:mm:ss.SSS} [%X{requestId:-}] %highlight(%-5level) %cyan(%logger{36}) - %msg%n</pattern>
        </encoder>
    </appender>

    <!-- ===== FILE APPENDER (Texto) ===== -->
    <appender name="FILE" class="ch.qos.logback.core.rolling.RollingFileAppender">
        <file>${LOG_PATH}/${APP_NAME}.log</file>
        <rollingPolicy class="ch.qos.logback.core.rolling.SizeAndTimeBasedRollingPolicy">
            <fileNamePattern>${LOG_PATH}/archived/${APP_NAME}.%d{yyyy-MM-dd}.%i.log.gz</fileNamePattern>
            <maxFileSize>50MB</maxFileSize>
            <maxHistory>30</maxHistory>
            <totalSizeCap>5GB</totalSizeCap>
        </rollingPolicy>
        <encoder>
            <pattern>%d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] [%X{requestId:-N/A}] [%X{userId:-anonymous}] %-5level %logger{50} - %msg%n</pattern>
        </encoder>
    </appender>

    <!-- ===== ERROR FILE APPENDER ===== -->
    <appender name="ERROR_FILE" class="ch.qos.logback.core.rolling.RollingFileAppender">
        <file>${LOG_PATH}/${APP_NAME}-error.log</file>
        <filter class="ch.qos.logback.classic.filter.ThresholdFilter">
            <level>ERROR</level>
        </filter>
        <rollingPolicy class="ch.qos.logback.core.rolling.SizeAndTimeBasedRollingPolicy">
            <fileNamePattern>${LOG_PATH}/archived/${APP_NAME}-error.%d{yyyy-MM-dd}.%i.log.gz</fileNamePattern>
            <maxFileSize>50MB</maxFileSize>
            <maxHistory>90</maxHistory>
        </rollingPolicy>
        <encoder>
            <pattern>%d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] [%X{requestId}] %-5level %logger{50} - %msg%n%ex</pattern>
        </encoder>
    </appender>

    <!-- ===== ASYNC APPENDER (Performance) ===== -->
    <appender name="ASYNC_FILE" class="ch.qos.logback.classic.AsyncAppender">
        <queueSize>512</queueSize>
        <discardingThreshold>0</discardingThreshold>
        <includeCallerData>false</includeCallerData>
        <appender-ref ref="FILE"/>
    </appender>

    <!-- ===== PERFIL DEV ===== -->
    <springProfile name="dev,local">
        <root level="INFO">
            <appender-ref ref="CONSOLE"/>
        </root>
        <logger name="com.myapp" level="DEBUG"/>
        <logger name="org.hibernate.SQL" level="DEBUG"/>
        <logger name="org.springframework.web" level="DEBUG"/>
    </springProfile>

    <!-- ===== PERFIL PROD ===== -->
    <springProfile name="prod">
        <root level="WARN">
            <appender-ref ref="ASYNC_FILE"/>
            <appender-ref ref="ERROR_FILE"/>
        </root>
        <logger name="com.myapp" level="INFO"/>
    </springProfile>

    <!-- ===== PERFIL TEST ===== -->
    <springProfile name="test">
        <root level="WARN">
            <appender-ref ref="CONSOLE"/>
        </root>
        <logger name="com.myapp" level="INFO"/>
    </springProfile>

    <!-- ===== DEFAULT (nenhum perfil) ===== -->
    <springProfile name="default">
        <root level="INFO">
            <appender-ref ref="CONSOLE"/>
            <appender-ref ref="FILE"/>
        </root>
        <logger name="com.myapp" level="DEBUG"/>
    </springProfile>

</configuration>

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7. Loggers Específicos Úteis

<!-- Requisições SQL do Hibernate -->
<logger name="org.hibernate.SQL" level="DEBUG"/>
<logger name="org.hibernate.type.descriptor.sql.BasicBinder" level="TRACE"/>

<!-- Spring Security -->
<logger name="org.springframework.security" level="DEBUG"/>

<!-- Requisições HTTP recebidas -->
<logger name="org.springframework.web.filter.CommonsRequestLoggingFilter" level="DEBUG"/>

<!-- Connection Pool -->
<logger name="com.zaxxer.hikari" level="DEBUG"/>

<!-- Transações -->
<logger name="org.springframework.transaction" level="DEBUG"/>

<!-- Desativar logs ruidosos -->
<logger name="org.apache.catalina" level="WARN"/>
<logger name="org.apache.tomcat" level="WARN"/>

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8. Resumo

Arquivos de Configuração

Arquivo	Uso
application.properties	Configuração simples
logback-spring.xml	Configuração avançada
logback.xml	Configuração sem Spring

Appenders Comuns

Appender	Uso
ConsoleAppender	Console (dev)
FileAppender	Arquivo simples
RollingFileAppender	Arquivo com rotação
AsyncAppender	Performance (prod)

Pattern Recomendado

%d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] [%X{requestId}] %-5level %logger{50} - %msg%n

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🎯 Próximo Passo

Hora da prática! Vamos implementar um sistema completo de gestão de erros e logging.

➡️ TP10.1: Gestão Centralizada de Erros

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⬅️ Voltar ao Módulo 10